This invention relates, in general, to power field effect transistors (FET), and more particularly, to a FET "H" Switch circuit having current sensing capabilities.
A typical field effect "H" switch circuit is disclosed in U.S. Pat. No. 4,454,454 which issued June 12, 1984 to Valentine. Such circuits are useful for providing bidirectional control to a load such as a motor. The "H" switch is suitable for motor drives and reversing switches. In applications where current sensing is needed it is usually achieved by sensing a voltage drop across a resistor in series with the "H" switch circuit. However, the power dissipated in such resistors reduces the efficiency of the circuit. Therefore, it would be desirable to provide an improved means for sensing current in an "H" switch circuit.
Accordingly, it is an object of the present invention to provide a method for sensing current in an "H" switch circuit which does not result in an appreciable loss of current.
Another object of the present invention is to provide a current sensing arrangement for an "H" switch circuit which does not appreciably deprive drive current from a load.
Yet a further object of the present invention is to provide a current sensing scheme at reduced cost useful in an "H" switch circuit.